The invention is directed to a method for mixing or blending batches of a flowable medium, especially hydrocarbons used as base materials for said media, and additives to be admixed thereto, and to a system for performing said method.
In the following description, the term batch or batches refers to the product which results from the bulk mixing or blending of solid or liquid ingredients in large amounts. It relates more particularly to a batch of a flowable medium such as base oil in an amount up to about 15 tons. In contrast, the additive materials which are mixed into the base oil, could be in an order of magnitude of several hundred grams.
Fully automatic mixing systems for oils, and additives to be admixed thereto are known. Such mixing systems normally comprise a weighing arrangement whose tanks are capable of holding a complete batch. Usually, the oils and additives are progressively weighed into this weighing tank. Admixing of minor additive quantities in the order of fractions of the complete batch is effected in a rather unprecise or crude manner.
For example, weighing arrangements of this type weigh out up to 50 tons of the bulk medium. The additional weighing of fractional or relatively minute amounts of modifier materials into the bulk medium, for example 200 grams of an additive, can be effected with little or no accuracy on a weight basis.
It is also known to use weighing arrangements to form blended lubricating liquids, utilizing a tank capacity of 800 to 1000 kg. It is true that these weighing arrangements are capable of weighing in desired amounts of the bulk material in a preliminary batch. It is difficult, however, to weight out with any degree of accuracy, batch fractions in the order of 200 grams of the components to be admixed into the preliminary batch.
Known bulk weighing arrangements having weighing tanks having 800 to 1000 kg capacity can be adapted to be mobile. The weighing tanks are thus capable of being moved to a tank truck or bulk storage tank. Alternatively, the tank's contents are transferred to larger storage or transport tanks. These operations are repeated until a sufficient quantity of finished blend has been produced.
It is an object of the invention herein disclosed, to provide a method of, and an arrangement for weighing out a preliminary batch of a base liquid media, which will be provided with a minor amount of additive material, the latter being blended into the base material in precisely weighed proportions.
The above-specified objective is achieved through use of an apparatus comprising a primary weighing section capable of holding a complete batch. The base material, and optionally certain additives, are weighed in to comprise a preliminary batch of the base medium. Independently, further additives amounting to minor fractions by weight of the overall batch, are formed in at least one precision weighing section. The precisely weighed-out additive fractions are then admixed into the bulky, weighed-out base medium.
In a primary weighing tank of the primary weighing section the major batch proportions, above all the base materials, are weighed out. This primary weighing section is capable of achieving a coarse weighing operation, which capability is sufficiently adequate for the large proportions of the base medium. In the precision weighing section of the system, precision weighing and forming of the fractional amount of additive material is then accomplished.
Following weighing-out a forming of the minor fractional amount of additives, the latter are introduced into the base medium where, however, only the total is weighed out. A signal, or other weight monitoring means, which can include a computer or the like, can be utilized for regulating or monitoring the flow of both the bulk material and the one or more additive fractions.
A system for performing the described method is characterized by a primary weighing section including a primary weighing tank for a complete batch, and at least one and preferably a plurality of precision weighing sections. The latter includes a precision weighing tank for holding additive quantities which are to be blended into the preliminary batch. The precision weighing tank for the additive quantities is adapted to be physically transferred or transported to the primary weighing tank. Liquid transfer means is provided for establishing temporary liquid transfer communication between the precision weighing tank for the additive quantities, and the primary weighing tank for the complete batch.
In accordance with a further embodiment of the invention the precision weighing portion of the arrangement is calibrated with numerical increments of about 10 to 20 grams, the maximum load of this segment being about 5 to 200 kg. Such precise metering increments are deemed adequate to provide accurate minor amounts of the additive material.
To physically transfer the precision weighing tank to the primary weighing tank, a further feature of the invention resides in a transfer system which is cooperative with the precision weighing tank for additive quantities. Said precision weighing tank is thus movable along a fixed transfer line by means of a carriage or dolly or the like.
The precision weighing tanks are characterized by a smaller width of access opening than the openings in the primary weighing tanks. As a consequence, the number of inlet valves for additives is limited in the instance of the precision weighing tanks. Since, however, a number of different additives must be weighed out and processed, plural precision weighing sections including precision weighing tanks are preferred.
In accordance with a further embodiment of the invention, when a plurality of precision weighing sections for additive quantities are utilized, the transfer line will extend between spaced apart rows of the bulk and precision weighing tank positions.
To enable and facilitate the simultaneous preparation of several batches a further embodiment of the invention provides that plural primary weighing sections are disposed in parallel to the transfer line. This arrangement facilitates transfer of the precision weighing tanks to the primary weighing tanks by means of a track or rail mounted carriage.
In accordance with a further aspect of the invention there is provided a tank elevating mechanism for raising tanks which holds additive materials up to a level exceeding the primary tank. It is also desirable to provide the elevating means with additional mixing means. It is further desirable to provide parking locations adjacent to the transfer line, where the respective additive tanks can be positioned.
Finally, it is provided that the primary weighing sections have a maximum load of about 15 tons. This maximum load design offers the advantage that the discrete, mixed batches will be comparable with the capacity of tank trucks which can then be loaded with either one batch or two batches.
Stated otherwise, there is hereinafter disclosed a system for forming or blending a batch of a flowable medium comprised of a major amount by weight of a hydrocarbon material, and a precise, or accurately weighed, minor amount of at least one additive material. The system includes a primary tank means for holding the major or bulk amount by weigh of the hydrocarbon material. At least one secondary tank, and preferably a plurality of secondary tanks are detachably communicable with a source or separate sources of additive materials.
Precise or accurate weighing means engageable with the at least one secondary tank, is operable to furnish a precise or fine indication of the weight of additive material, which is metered into said secondary tank, from a source of said material.
A transfer line extending between the primary tank and said plurality of secondary tanks includes guide means such as a set of tracks, rails or the like. A carriage which operably engages the track, functions to conveniently transport additive holding tanks.
Thus, a precisely weighed amount of additive material contained in at least one secondary tank can be conveyed along said transfer line to said primary tank. The precise amount of additive materials can then be blended into the major or bulk amount by weight of the hydrocarbon in said primary tank.